William a



W A. BRAUN.

METHOD OF MANUFACTURING ELECTRICALLY HEATE D DEVICES. APPUCATION FILED JULY 23.1914.

1 24,582. Patented Dec. 9,1919.

UNITED STATES PATENT OFFI E.

WILLIAM A.

nnAuN, or CANAL DOVER, OHIO, ASSIGNOR'TO THE novnn MANUFACTUR- ING COMPANY, or novnn, 01110, "A CORPORATIO or OHIO.

METHOD or MANUFAC URING ELECTRICALLY-HEATED DEVICES.

-cd new and useful Methods of Making Electrically-Heated Devices, of which the following is a specification.

Theinvention relates to improvements in the process of manufacturing and combin ing the several elements of electrically heat- I ed sad irons, stoves and other heating de vices,and thesame is described by reference to the accompanying drawings, in which Figure 1 represents a plan view of the smobthing plate or a sad ironwith alayer.

of electric insulating and heat conducting material for supporting a heating coil;

Fig. 2 a plan, view of the smoothing plate showing heating wire embedded in a layer of electric insulating and heat conducting material; p Fig. 3, a plan view of the smoothing plate, the layers of supporting material, the heating wire embedded in such material, and the upper metallic plate in place upon the upper layer of supporting material; ,tthe upper plate and one of the layers of supporting material being partly broken away to show the interior construction; and

Fig. 4, a transverse section drawn through the smoothing plate and the other cooper= ating parts. Like parts are identified by the same reference numerals throughout the several views. Y

a While I have shown and described myinvention as more especially adapted to be used in connection with sad irons, I wish it to be understood that substantially the same method may be employed in manufacturing heating apparatus for stoves, percolators, chafing dishes and for. numerous other heating purposes.

material when treated as herein set forth,

is not only a good insulator or electricity,

. of heat, whereby the heat of-electric wires is'conducted to the surface of the inclosure for any of the several numerous purposes named. v

In carrying out my method in sad irons,

Specification of Letters Patent.

Experience has also demonstrated the fact that the supporting;

Patented Dec; 9, 1919.

Application filedJ'uly 23, 1914. Serial N 0. 852,717.

I first form a cast metal smoothing plate 1, the lower surface 2 of which is polished. The smoothing plate is provided around its marginal edge with a continuous vertical flange 3, the space within which forms a receptacle 4: for the reception of the wire supporting material 5. The supporting material 5 may be of any suitable heat conducting electric insulating substance or composition, but I prefer to use a clay which is known as bauxite. This clay is subjected to a heat of approximately 8000 Frin an electric furnace, when it becomes vitrified, whereupon it is taken out in large hard lumps, which are then crushed under large steel rollers until all the particles are reduced to fine grains, in which form it can be obtained on the open market. lit is in this form that this material may be used in my electric iron by simply adding water and a suitable binder to make the mix ture' semi-plastic.

The receptacle 1 is preferably heated to a temperature of about 212 F. wheh a layer of the electric insulatin heat-conducting material 5 is placed therem and thoroughly dried: When such material has been thoroughly dried, a second layer 5 of the same 'material is placed thereon in a semi-plastic condition. When this is done a coil or heating wire 6 is embedded in said material, when a third layer 6" of the sameimaterial is placed upon and above said second layer and the heating coil, whereupon the whole is thoroughl dried. 3

. When t e several layers of material have been thus thoroughly dried, the whole is subjected to a high pressure of approximately sixty tons for-the surface of an ordinary. sad iron. When the device has been thus subjected to a high pressure, it is placed in a heating oven and subjected to a high temperature of approximamly 12009 F. TllS temperature is maintained until the electric insulating heat conducting supporting ma-' terial becomes extremely hard.

Experience has demonstrated the faet that when the constituent parts are subjected to a high pressure and temperature as described, the. supporting. material is brought thereby into close contact both with the mclosure and with the heating wires, whereby the electric conductor is not only perfectly insulated but the heat generated by said conductor is rapidly conducted through said supporting material to the metal of the receptacle.

Also owing to the fact that the heating wire is brought into such close contact with its supporting material, and to the fact that the particles of the supporting material are' brought into close contact with each other, the heat is rapidly conducted away and the wire is prevented from becoming excessively heated, as it might otherwise be if supported in a less perfect heat conductor. When the supporting material has been thus pressed and heated, experience has demonstrated that it will absorb but little moisture from the atmosphere.

An .additional metal plate 7 may be screwed in place above the supporting material by bolts or screws 8 and 9. The plate 7 is preferably provided with apertures 10, 10 for the reception of the ends 11 and 12 of the heating coils 6. 13, 13 are insulating bushings by which the ends of the heating coils 11 and 12 are prevented from coming into direct contact with the metallic plate 7. It will be understood that the respective ends 11 and 12 of the heating coils are adapted to be connected with a source of electrical energy in the'ordinary manner; and also that an operating handle and other cooperating mechanism is adapted to be connected with the receptacle in any convenient manner the invention herein being predicated, as stated, more especially upon the method of making and combining the elements of the heating unit per se in the manner substantially as set forth.

What I claim is:

l. The method of making electrical heating units consisting in forming and drying a layer of electric insulating heat conducting supporting material, then placing thereon a second layer of the same supporting material in a semi-plastic condition, then embedding a resistance element in said second layer, then placing thereon a third layer of the same supporting material, and then drying the whole and subjecting it to a high pressure and to a high temperature.

2. The method of making electrical heating units consisting in providing a metallic receptacle, forming and drying a layer of electri insulating heat conducting material in the receptacle, then placing thereon a second layer of the same supporting material in a semi-plastic condition, then embedding a resistance element in said second layer, then placing thereon a third layer of the same supporting material, and then drying the whole and subjecting it to a high pressure and to a high temperature.

In testimony whereof I aiiix my signature in the presence of two witnesses.

/VILLIAM A. BRAUN.

Witnesses J. M. MILLER,

Onor Horn, Jr. 

